Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-12-07
2002-05-28
Nguyen, Lee (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S426100, C455S432300, C455S433000, C455S436000
Reexamination Certificate
active
06397065
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to mobility management in cordless communications systems and specifically to location updating in a cellular radio access network.
BACKGROUND OF THE INVENTION
Currently under development are third generation mobile communications systems, such as the Universal Mobile Communication System (UMTS) and the Future Public Land Mobile Telecommunication System (FPLMTS), which has later been renamed as IMT-2000 (International Mobile Telecommunication 2000). The UMTS is under standardization at European Telecommunication Standards Institute (ETSI), while the International Telecommunication Union (ITU) is standardizing the IMT-2000 system. These future systems are very similar in their basic features. In the following, the UMTS system will be dealt with in more detail.
Like all mobile communications systems, the UMTS provides cordless data transmission services for mobile users. The system supports roaming, in other words, UMTS users can receive and make calls anywhere, as long as they are located within the UMTS coverage area. The UMTS is anticipated to satisfy a wide variety of future service needs, such as high-speed data services (multimedia), and video services, such as video calls. Many future services that will be needed are difficult to envision today. The use of the different services is also difficult to forecast, for which reason it is not possible to optimize the UMTS to one group of services only. One conclusion from this is that the UMTS must be constructed to be versatile and to permit further development. For this reason, a modular approach of the network architecture has been adopted, making it possible to implement the UMTS effectively in different environments.
In the present perception, UMTS is built up of two or three parts that are illustrated in FIG.
1
: a UMTS access network
1
(or a UMTS base station system, UMTS-BSS) and a core network
2
,
3
,
4
and
5
. In the following, the UMTS access network will also be generally termed a radio access network. The UMTS access network
1
is mainly responsible for things related to the radio path, i.e. it offers to a core network a radio access that is needed for cordless operation. The core network
2
,
3
,
4
or
5
is a conventional or future telecommunications network modified to effectively utilize the UMTS access network in cordless communication. Telecommunications networks that have been contemplated as suitable core networks include second generation mobile communications systems, such as GSM (Global System for Mobile Communication), ISDN (Integrated Services Digital Network), B-ISDN (Broadband Integrated Services Digital Network), packet data networks PDN (Packet Data Network), ATM (Asynchronous Transfer Mode), and so on.
Accordingly, the UMTS access network must be capable of providing support to various core networks, also those evolving in the future. Likewise, UMTS access networks should permit connection of various radio interfaces to a core network (narrow-band, broadband, CDMA, TDMA, etc.). Several service providers SP
2
to SP
5
providing different services to UMTS subscribers may be connected to the core networks
2
to
5
. The core networks mainly produce bearer capabilities and the service providers SP may define their own services utilizing these bearer capabilities. In theory, the core network shall be capable of supporting services defined by any SP. This contributes to the possibility of the user being connected to one core network and being simultaneously active in different services of different service providers. The UMTS access network may also be simultaneously connected to several core networks. Consequently, the access network must be capable of supporting different core networks and/or services and their subscribers simultaneously.
One of the most important demands on cordless communication is subscriber mobility management. Because a subscriber does not have a fixed access point at cordless communication, information on a subscriber's location at each moment must be maintained with a suitable accuracy in the registers of the network. The location data may tell for instance the subscriber's present cell, but preferably it indicates the subscriber's present location area comprising several cells. At a cell or location area handover, the mobile station always sends the network a location updating request, which causes an updating of location data in the registers of the network. By using larger location areas, the load caused by location updatings on the radio path can be reduced. A drawback is that paging messages have to be sent the mobile station in all cells of the location area. The size of the location area generally is a compromise between location updating signalling and paging signalling.
As stated above, the UMTS access network may be connected to more than one core network CN or the UMTS subscriber may be active in several services. Each core network may have a dedicated mobility management protocol (MM) and dedicated location areas (LA). Likewise, each service may have a dedicated location management. For this reason, the UMTS access network has to send location area identities of all core networks CN on its signalling channel. Thus each subscriber terminal, being active in one or more core networks, may monitor the broadcast location area identities of the desired core network
etworks and send a location updating message to the access network when moving across the boundary of some location area. If the boundary of the location area of several different core networks is crossed simultaneously, the subscriber terminal has to send many location updating messages over the air interface, one for each core network and/or service involved. This causes significant signalling load over the radio interface. This is against normal planning objectives trying to minimize the amount of MM messages and the signalling over the radio interface in general.
At the development of the UMTS access network, an open question is how a uniform MM protocol supporting different core networks CN and services can be implemented therein and how the amount of MM messages especially over the radio interface can be minimized. An idea has been presented that the very UMTS access network should comprise some kind of a subscriber register, in which location data are managed. Even such thoughts have been presented that an access network cannot operate without dedicated registers. However, registers require dedicated interfaces in the core networks CN or to an intelligent network IN. In addition, a specific mobility management protocol should be standardized in the access network. If separate registers could be left out, standardizing and planning work would be saved, and moreover, radio access network products would be simpler and cheaper.
DISCLOSURE OF THE INVENTION
An object of the invention is to minimize the location updating signalling to be sent over the radio interface in the systems described above.
Another object of the invention is to avoid separate subscriber registers in a radio access network.
A feature of the invention is location updating methods according to claim 1 and 16.
Another feature of the invention is cellular radio access network according to claim 10.
A radio access network is connected to one or more core networks or services, each of them having dedicated location areas and/or location management protocols. Each cell of the radio access network sends identities of those location areas to which the cell in question belongs. A subscriber terminal monitors the broadcast location area identities and sends a location updating message to the radio access network or a core network at a handover from an old cell to a new cell, if some of the location area identities broadcast by the new cell differs from the location area identities broadcast by the old cell, the old location area identities being stored in the subscriber terminal. In the invention, the subscriber terminal sends, however, only one location updating m
Bäck Juha
Einola Heikki
Huotari Seppo
Huusko Sami
Lahtinen Lauri
Nguyen Lee
Nokia Telecommunications Oy
Pillsbury & Winthrop LLP
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